Improved mode of repairing files



UNITED STATES A. A. DUNK, OF MANCHESTER, NEW HAMPSHIRE.

IMPROVED MODE OF REPAIRING FILES.

Specification forming part of Letters Patent No. 56,734. dated July 31, 1866.

To all whom t may concern: Y

Be it known that I, A. A` DUNE, of Man chester, Hillsborough county, State of New Hampshire, have invented a new -and useful Improvementin Cutting Files; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l represents a tile part of which has been recut according to my invention. Fig. 2

-represents a roller which may be used in carrying out the invention.

Similar letters of reference indicate like parts.

This invention consists in a new process of recutting and renewing worn tiles, and such as arebadly cut and damaged, so as to make them serviceable.

The details and explanation of the process and invention are as follows: I take, for instance, a worn outfile, or a file poorly out, and clean it well from dirt and foreign matter. I then coat the top of the file-that is to say, the prominences or teethwith a varnish capable of resisting the action of acids, and immerse it in a bath ofy acid, keeping it therein until the intervals between the teeth have been eaten away by the acid to a suitable depth.

The varnish which l have used is made as follows: twelve parts, by weight,ofasphaltun1 nine parts, by weight, of black pitch; one and one-half part, by weight, of Burgundy pitch three parts by weight, of resin; eighteen parts, by weight, of bees-wax. These ingredients are dissolved together in turpentine, which is supplied in sufficient quantity to bring them to a liquid form.

I do not claim the composition of this varnish, and any other varnish or material which will resist the action of acids and acidulous preparations will answer the purpose required.

The varnish or other material is applied tol the surfaces ofthe file by means of a roller, such as is shown vin Fig. 2, its periphery being covered by a brous or other covering which can be saturated with the varnish or by means of a roller of any other suitable construction, or by means of any suitable implement, the object being to distribute the varnish or protecting material uniformly on the points or teeth of the file which the roller will come inA contact with on being passed to and fro over them in a way similar to that used in distributing ink on the surfaces of type; but the varnish or protecting coating must not cover the interspaces.

When the points of the teeth are well proteoted the file is immersed in a bath of nitric or any other acid or acidulous preparation' which will corrode or eat away the metal, and when the intervals between the points of the teeth are sufciently deepened and the proper sharpness is produced, the tile is removed from`the bath and the coating is taken off by being melted away, or by rubbing, or in any other convenient manner.

The lile shown in Fig. l is an old one, a part of which (marked A) has been treated by my process and renewed, so as to be ready for use, and a part (marked B) has been left dull.

I claim as new and desire to secure by Letters Patent- The process of sharpening and renewing files, substantially as above described, by eovering the tops ofthe teeth only with a protecting-coating, and then immersing the tile in acid until the intervals are sufficiently deepened.

A. A. DUNK.

Witnesses:

ARCHE. M. GRAHAM, GEO. A. FRENCH. 

